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The continuous integration of renewable energy sources into power systems has led to the construction of large power plants based on power electronics, with power ratings up to hundreds of megawatts, in order to accomodate technologies like solar PV and wind energy. Due to the size of these plants, they must provide support services for the grid and it is necessary to analyze the impact they have...
Installing the battery energy storage in the interlinking converter of hybrid AD-DC grid can effectively reduce the exchanged energy of hybrid grid and therefore reduce the losses. Being different from the two-level or three-level interlinking converter for low voltage grid application, this paper proposes an interlinking modular multilevel converter (MMC) with integrated battery energy storage for...
In electric vehicle (EV) systems, bi-directional DC/DC converters are applied to interface the battery bank with the high voltage DC-link of the inverter. The control of the DC-link voltage is important for the high performance of the system. A DC-link voltage control strategy for the bidirectional DC/DC converter is proposed, which eliminates the need for detecting the operating mode and do not need...
This paper presents an isolated type of single-phase matrix converter topology for PHV/EV on-board battery chargers. The proposed converter is comprised of a full bridge inverter, a high frequency transformer and a matrix converter. Due to the lack of DC link bus in matrix converter, in order to suppress the power fluctuation, a power decoupling method which only employs a center-tapped high frequency...
A high-efficiency high-energy-density buffer architecture is proposed for power pulsation decoupling in power conversion between DC and single phase AC. We present an active decoupling solution that yields improved efficiency and reduced circuit complexity compared to existing solutions. By connecting a buffer converter in series with the main decoupling capacitor, the main capacitor is allowed larger...
Small-signal characteristics of synchronous Buck DC-DC converters under light load conditions are analyzed in this paper. Results of the analysis show that similar to non-synchronous Buck converters operating in discontinuous conduction mode, the double pole of the converter control-to-output voltage transfer function can be split into two real poles under certain conditions. The mechanism of such...
The utilization of multi-cell converters, based on low voltage semiconductors, has allowed the implementation of AC drives and PV farms in medium and high voltage levels. The conventional converter uses in the grid side a multipulse transformer that performs the cancellation of low frequency current harmonics, which are generated by the three-phase diode-based rectifiers included in the power cells...
This paper presents a comparative study of direct power control (DPC) and model predictive control (MPC) for three-level neutral-point-clamped (NPC) AC/DC converters. The operating principle of DPC and MPC are introduced in detail, with focus on vector selection mechanism and suppression of neutral point voltage fluctuation. Special care is given to the avoidance of high voltage jumps in both phase...
This paper presents two discontinuous pulse width modulation (DPWM) methods for three phase Vienna rectifiers with different performance optimization targets. One for switching loss minimization and one for switching loss reduction with the neutral point voltage controllability. Due to the current commutation characteristics if Vienna rectifiers, the available space voltage vectors are limited. With...
A cascaded brushless doubly fed induction machine (CBDFIM) drive with the same active rotor volume and comparable extended constant torque and constant power regions as those of the doubly fed induction machine (DFIM) is proposed and theoretically demonstrated. To achieve the appealing goal, the drive system is configured to supply the power winding with a constant voltage constant frequency (CVCF)...
In this paper, an improvement in power sharing for Autonomous Microgrid is well established. All previous studies were based on voltage and frequency droop control to share power between distributed generators. This paper develops a new robust voltage and angle droop control to share power, where its advantage over the common frequency droop is in less frequency variation. The synchronization of Power...
Droop control is a widely used technique for load sharing in DC microgrids (MGs); however, its performance is affected significantly by the voltage drops over coupling line impedances causing load sharing errors and voltage degradation across MG bus. Therefore, the locations of the sources in the MG and loading conditions (LCs) have considerable effect on load sharing accuracy and voltage regulation...
Micro-grid should be able to operate in both islanding mode and grid-connected mode, but how to transfer smoothly between these two modes is a question. This paper presents a seamless transition strategy for droop-controlled inverters to operate in both islanding and grid-connected modes and transfer smoothly between these two modes. The control principle and pre-synchronization control strategy are...
The grid-feeding voltage controlled inverter (GF-VCI) based on droop control is vulnerable to the harmonic voltages of the utility grid. Because of the equivalent impedance of system is small, the slight distorted grid voltage will result in the harmonic component increasing of GF-VCI output currents. Therefore, the reason of generation of distorted grid-feeding current of GF-VCI under the distorted...
The concept of microgrid can integrate large amounts of Distributed Generations (DG) into power system and provide higher reliability, energy security and surety to critical loads. A Virtual Droop Control (VDC) method is proposed for the power management and voltage and frequency regulation and has been applied to the Fort Sill microgrid. The state space models for the microgrid components and systems...
The series-stacked architecture provides a method to increase power delivery efficiency to multiple processors. With a series-stack, Differential Power Processing (DPP) is needed to ensure that processor voltages remain within design limits as the individual loads vary. This work demonstrates a switched-capacitor (SC) converter to balance a stack of four ARM® Cortex-A8 based embedded computers. We...
Current data center power delivery architectures consist of many cascaded power stages, where the system-level efficiency is dependent on the efficiency of the power elements. Recently, series-stacked power delivery architectures eliminated this dependency and reported more than 99% system-level power conversion efficiencies for data centers. In this paper, we address the important start-up and hot-swapping...
An effective output voltage regulation method using harmonic burst mode control strategy is presented. By using this strategy, the operating performance of the full-bridge series resonant dc-dc converter (SRC) applied to electric vehicle (EV) battery charging is improved. The proposed control strategy not only performs load regulation, but it also achieves soft switch both at turn-on and turn-off...
Integrated charger topologies that have been researched so far are with the dc-dc converters and the charging functionality usually have no isolation in the system. Isolation is an important feature that is required for user interface systems that have grid connections and therefore is a major limitation that needs to be addressed along with the integrated functionality. This study features a unique...
This paper proposes a modulation scheme for a dual-active-bridge (DAB) converter to reduce current conduction in wide-range operating conditions. The operating principle of the proposed fundamental duty modulation (FDM) is formulated based on the fundamental component analysis (FCA) of the DAB converter. By modulating the PWM signals in the fundamental component domain, the circulating current can...
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